1. Field
Example embodiments relate to a complementary metal-oxide semiconductor (CMOS) image sensor (CIS) and a method of manufacturing the same. More particularly, example embodiments relate to a CIS having a backside illumination (BSI) architecture and a method of manufacturing the same.
2. Description of the Related Art
Image sensors convert optical signals to electrical signals. As the information and communication industry are becoming more developed and electronic equipment is becoming digitized, image sensors may be used in many devices, e.g., digital cameras, camcorders, mobile phones, personal communication system (PCS) phones, game consoles, and/or medical micro video cameras.
In order to increase the resolution of images, pixels of an image sensor may be highly integrated. However, as the pixels become highly integrated, the area of a photoelectronic conversion device, e.g., a photodiode per unit pixel, becomes smaller, thereby decreasing sensitivity.
Generally, if sensitivity becomes small according to the reduction of the photodiode area, the sensitivity may be increased by increasing an amount of light incident on the photodiode. In a typical complementary metal-oxide semiconductor (CMOS) image sensor (CIS), light may be incident on a front surface of an image sensor cell and may penetrate the image sensor. While the incident light penetrates the image sensor cell, e.g., a thick insulation layer, a large amount thereof, especially, a large amount of red color light having a long wavelength, may be absorbed by the insulation layer, thereby decreasing light efficiency.
Thus, backside illumination (BSI) technology has been introduced to solve the problem. In a method of manufacturing a CIS having a BSI architecture, metal wirings of circuits may be formed on a front surface of a substrate, and color filter layers and microlenses may be formed on a rear surface thereof. However, when the color filter layers and the microlenses are formed on the rear surface, alignment keys that may be used for forming the metal wirings may not be easy to recognize, and thus, the color filter layers and the microlenses may not be well aligned with the metal wirings.